The phosphorylation of nonhistone chromosomal proteins (NHCP) appears to exert a regulatory influence on transcription in eukaryotic cells. The effects of adenosine analogs upon NHCP phosphorylation will be further explored by analyzing the phosphorylation of a discrete class of NHCP called the high mobility group (HMG) proteins in Ehrlich ascites cells in vitro. The association of phosphorylated HMG proteins with transcriptionally active and inactive regions in chromatin will be determined by selective nuclease digestion of nuclei.